let arrOFNumbers : number[] = [1,2,3]
arrOFNumbers.push('hello')
arrOFNumbers.push(1)

function test(){
    console.log(arguments);
    arguments[0]
    let arr: any[] = arguments
    let htmlCollection:HTMLAllCollection
}

// 元组
let user: [string , number] = ['str',120]
user.push(1,'123')

// interface 接口
// 对对象的形状(shape) 进行描述
// Duck Typing（鸭子类型）
interface Person {
    readonly id :number
    name:string;
    age?:number;
}

let viking:Person = {
    name:'str',
    age:18,
    id:10
}

viking.id = 199